Flat File Handling in VB.Net using FileStream & StreamWriter Classes:

Imports System.IO
Public Class Form1
Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

Public Sub New()
MyBase.New()

'This call is required by the Windows Form Designer.
InitializeComponent()

'Add any initialization after the InitializeComponent() call

End Sub

'Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub

'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer

'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
Friend WithEvents Button1 As System.Windows.Forms.Button
Friend WithEvents TextBox2 As System.Windows.Forms.TextBox
Friend WithEvents Button2 As System.Windows.Forms.Button
Private Sub InitializeComponent()
Me.TextBox1 = New System.Windows.Forms.TextBox()
Me.Button1 = New System.Windows.Forms.Button()
Me.TextBox2 = New System.Windows.Forms.TextBox()
Me.Button2 = New System.Windows.Forms.Button()
Me.SuspendLayout()
'
'TextBox1
'
Me.TextBox1.Location = New System.Drawing.Point(112, 8)
Me.TextBox1.Name = "TextBox1"
Me.TextBox1.Size = New System.Drawing.Size(224, 20)
Me.TextBox1.TabIndex = 0
Me.TextBox1.Text = ""
'
'Button1
'
Me.Button1.Location = New System.Drawing.Point(352, 8)
Me.Button1.Name = "Button1"
Me.Button1.TabIndex = 1
Me.Button1.Text = "Create File"
'
'TextBox2
'
Me.TextBox2.Location = New System.Drawing.Point(112, 40)
Me.TextBox2.Multiline = True
Me.TextBox2.Name = "TextBox2"
Me.TextBox2.Size = New System.Drawing.Size(312, 160)
Me.TextBox2.TabIndex = 2
Me.TextBox2.Text = ""
'
'Button2
'
Me.Button2.Location = New System.Drawing.Point(224, 208)
Me.Button2.Name = "Button2"
Me.Button2.TabIndex = 3
Me.Button2.Text = "Save File"
'
'Form1
'
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(536, 266)
Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.Button2, Me.TextBox2, Me.Button1, Me.TextBox1})
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)

End Sub

#End Region
Dim Fstream As FileStream
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim strPath As String
strPath = TextBox1.Text
Fstream = New FileStream(strPath, FileMode.OpenOrCreate)
End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Try
Dim Swriter As StreamWriter = New StreamWriter(Fstream)
Dim strContent As String
strContent = TextBox2.Text
Swriter.Write(strContent)

Swriter.Close()
Fstream.Close()
Catch IoEx As IOException
MessageBox.Show(IoEx.Message)
End Try
End Sub
End Class